Effect Of β-glucan On Obesity And Obesity-resistant Rats With Nonalcoholic Fatty Liver Disease

BackgroundIn the past 10 years, the prevalence rate of fatty liver disease, especially non-alcoholic fatty liver disease (NAFLD) had obviously increased. In Shanghai China, the prevalence rate is 20.82% close to foreign countries. In western countries, fatty liver has become the most common liver disease. In China, fatty liver also has replaced viral hepatitis as the most common liver disease trends. However, the clinical significance of hepatic steatosis is controversial. A long time, people think fatty liver is a kind of disease with good prognosis, especially when these fatty liver patients with normal serum aminotransferase. But in recent years, more and more studies have found fatty liver are closely related with many life-threatening diseases.Non-alcoholic fatty liver and obesity are closely related. The study found that liver fat metabolism has related with the metabolites, hormones, cytokines and nerve media such as tumor necrosis factor-α, leptin, adiponectin and so on. Metabolism of fatty liver is not only the undesirable result of dysbolism, it can also trigger signal makes the normalization of liver fat metabolism. But it inevitably also changed the activity of cytokines, hormones and neural in the other organizations. These factors interact to cause neurohumoral and immune system dysfunction, leading to insulin resistance and metabolic syndrome happen.D-glucan(1→3) (1→4) is a kind of polysaccharide extracted from oats or barley and belongs to soluble dietary fiber. Experimental study has confirmed that oatβ-glucan has the functions such as anti-oxidation, reducing blood fat, lowering blood sugar, protecting liver function, and promote the growth of intestinal probiotics, etc. But these studies only confined to single disease in experimental animal models or treatment. The study about mechanism is still less.This study is based on the latest research progress of NAFLD and obesity, with high-fat and high-energy feed prepared animal model which has the clinical features of NAFLD with obesity and obesity-resistant. It aimed to find out the relationship between obesity and NAFLD, and the role of obesity in the occurrence and development of NAFLD. Using real-time fluorescence quantitative PCR technique studies the expression and regulation of PPAR-γand UCP2 in obesity and obesity-resistant NAFLD rats. And takingβ-glucan and diet intervention study for 4weeks observed the function, in order to further explore the mechanism and prevention of NAFLD and provide experimental basis for health food products.PartⅠPrepare obesity and obesity-resistant model in nonalcoholic fatty liver ratsObjective To use high-fat and high-energy feedstuff prepare obesity and obesity-resistant model in nonalcoholic fatty liver rats.Method 20 male Sprague-Dawley (SD) rats were randomly selected according to the weight as control group, the remaining 120 for the model group. After 8 weeks, the average weight of +1.96 times the standard deviation divided into O-N group and the average weight of +1.0 times the standard deviation and divided into OR-N group. Observed the rats'general condition, diet changes, behavior (self-activity, mental status) changes, hair changes, weight of feed every day and body weight. Monitoring blood glucose and blood lipids situation is at 0, 4 and 8week. At 8 week, 8 rats of every group were killed randomly and collected specimens to detect liver index, serum ALT, AST, TC, TG and hepatic pathology.Result The weight of O-N group was significantly higher than OR-N group and the normal control group. ALT and TG of O-N and OR-N group were significantly increased, while the O-N serum TC, TG was significantly higher than OR-N group; two groups of liver weight and liver index were significantly increased, O-N group liver weight and body weight were significantly higher than the OR-N group, but liver index no significant differences between. O-N and OR-N group hepatic lobules were structural damaged, hepatic cord disordered, hepatic sinusoid expansion and hepatocellular swelled obviously.PartⅡdifference between obesity and obesity-resistant rats in non-alcoholic fatty liverObjective To study the metabolic difference between obesity and obesity-resistant rats in non-alcoholic fatty liver.Method 24 male Sprague-Dawley (SD) rats were separately from the control, O-N and OR-N group. In each group were randomly selected 8 rats, obesity tendency for ON group, obesity resistance for OR-N group and normal control group. At 8 week, the rats were fasted for 12h later, with 10% chloral hydrate anesthesia, taken blood, and determinate TC, TG, HDL, LDL, Leptin, Il-6, TNF-α, blood sugar and calculation of insulin sensitivity index. Observed the main organ, weigh adipose tissue pad around kidney and testicle and calculated body fat ratio. Keeping left perirenal adipose tissue in 10% formalin solution for adipose tissue pathology and preserving hypothalamus in liquid nitrogen for determinating NPY content.Result O-N rats'the utilization rate of energy intake was significantly higher than OR-N group and the control group. The fat pad weight, FINS, ISI, Leptin and NPY content in the hypothalamus and serum of O-N group were significantly higher than the normal control group and the OR-N group, but body fat ratio between the two groups, TNF-α, IL-6, FBG and LDL were no significant difference. O-N group and OR-N rats'left perirenal fat cell diameter had significant increased and the volume become larger.PartⅢUCP2 and PPARγ2 in obesity and obesity-resistant non-alcoholic fatty liver ratsObjective To study the UCP2 and PPARγ2 in obesity and obesity-resistant non-alcoholic fatty liver rats.Method Using the two-step real-time fluorescence quantitative reverse transcription polymerase chain reaction to detect PPARγ2 and UCP2 mRNA expression in adipose and liver tissue.Result UCP2 mRNA expression of OR-N group in liver and adipose tissue was significantly higher than O-N group and normal control group and the PPARγ2 mRNA expression in the adipose tissue was significantly lower than the control group. O-N group relative liver UCP2 mRNA expression was significantly lower than control group, the adipose tissue of PPARγ2 mRNA relative expression was significantly higher than both OR - N group and normal control group.PartⅣthe effect ofβ-glucan and restoration of normal diet for obese and non-alcoholic fatty liver ratsObjective To study the effect ofβ-glucan and restoration of normal diet for obese and non-alcoholic fatty liver rats.Method 56 male Sprague-Dawley (SD) rats were separately from the control, O-N and OR-N group. O-N and OR-N group were randomly divided into 3 groups of 8 only, namely ON-1 Group, ON-2 Group, ON-3 group and the OR-N-1 group, OR-N-2 group, OR-N-3 group; eight normal rats as control group. Control group eating normal diet; ON-1 and OR-N-1 group 500mg/kg.d-1β-glucan administered intervention; ON-2 and OR-N-2 group high-fat diet group sustained; ON-3 and OR-N-3 group returned to normal diet. After 4 weeks intervention, the rats were fasted for 12h later, with 10% chloral hydrate anesthesia, taken blood, and determinate TC, TG, HDL, LDL,ALT and AST. Observed the main organ, weigh adipose tissue pad around kidney and testicle and calculated body fat ratio. Keeping left liver tissue in 10% formalin solution for liver tissue pathology and preserving left liver tissue in liquid nitrogen for determinating SOD and MDA content.Result O-N weight in each group was still significantly higher than the normal control group, OR-N-1 group and the OR-N-2 group body weight also significantly increased. O-N-2 group and the OR-N-2 rats body fat ratio was significantly increased; ON-1 group and the OR-N-1 group body fat ratio although still higher than the normal control group, but compared with the same group 2, both downward trend; ON-1 group and ON-3 rats compared with ON-2 group, body fat ratio decreased significantly, OR-N-3 rats compared with OR-N-2 group, body fat ratio decreased significantly. O-N-2 group of TC, TG, LDL significantly increased, while HDL significantly reduced, OR-N-2 group of TG, LDL significantly increased; and compared with O-N-2 group, O-N-1 group TC decreased significantly, O-N-3 Group TG significantly decreased, HDL increased significantly;and compared with OR-N-2 group, OR-N-1 group had a significant reduction in TG. O-N-2 Group ALT, liver index was significantly higher than the normal control group and O-N-3 group; OR-N-2 group ALT was significantly higher than the normal group and the OR-N-3 group, liver index was significantly higher than the normal group; each group no significant differences in AST. O-N-1 group and the OR-N-1 group SOD activity was significantly higher than the normal group, ON-2 group and the OR-N-2 group SOD activity was significantly lower than the normal group; MDA content of O-N-1 group and O-N-3 group was significantly lower than the O-N-2 group, OR-N-1 group was significantly lower than the OR-N-2 Group, O-N-2 group and the OR-N-2 group was significantly higher than the normal group.Conclusions1. Successfully create the obesity and obesity-resistant non-alcoholic fatty liver rat model with high-fat and high-energy feed2. We found obesity and obesity-resistant non-alcoholic fatty liver rats has increased body fat ratio, glucose, TNF-α, IL-6 and dyslipidemia, the phenomenon of insulin resistance, dyslipidemia is the causes of non-alcoholic fatty liver.3. Obesity resistance are probably happened because of visceral adipose tissue UCP2 mRNA expression levels increased and PPARγ2 mRNA expression was inhibited, reducing leptin resistance and insulin resistance, lowering NPY content, thereby reduced the energy intake and utilization rates, increased energy consumption and avoided the occurrence of obesity.4. Liver tissue UCP2 mRNA expression levels significantly increased, and probably had more than the compensatory ability of the body and have an adverse impact on liver injury.5. Return to normal diet or the intervention ofβ-glucan can inhibit weight gain in obese tend rats, reduce serum cholesterol and body fat content and improve nonalcoholic fatty liver.6. Under the high-fat and high-energy diet-induced, the weight gain of obesity-resistant rats tend to start faster than obese rats, suggesting that long-term high-fat diet may lead to obesity-resistant rats fat.